1. Field of the Invention
The present invention relates to a semiconductor module and a method of manufacturing the same, and more particularly to a semiconductor module, which has semiconductor elements and the like mounted on both surfaces of a substrate, and is highly reliable, and a method of manufacturing the same.
2. Description of the Related Art
Referring now to FIGS. 7A to 7C, a method of manufacturing a conventional double-sided surface mount type circuit module is described.
Referring to FIG. 7A, a circuit board 101 is first prepared, which includes a substrate 102 having a first conductive pattern 103 which is formed on the front surface thereof and a second conductive pattern 104 which is formed on the back surface thereof.
Referring to FIG. 7B, a first semiconductor element 105 is mounted on the first conductive pattern 103, and second semiconductor elements 106 are mounted on the second conductive pattern 104. At this time, devices for mounting the semiconductor elements are mounted above and beneath the circuit board 101. The first and second semiconductor elements 105 and 106, respectively, are mounted substantially at the same time.
Referring to FIG. 7C, the first and second semiconductor elements 105 and 106, respectively, are electrically connected with the conductive patterns via thin metallic wires 108A and 108B, respectively, to form an electric circuit. Furthermore, after making a resin seal using an insulative resin, the electric circuit is separated into predetermined shapes to manufacture a double-sided surface mount circuit module. This technology is described for instance in Japanese Patent Application Publication No. 2004-63618.
However, there have been following problems with the method of manufacturing the circuit module described above.
For example, in a case where wire bonding of the first semiconductor element 106 is performed after wire bonding of second semiconductor elements 105, it becomes necessary to prevent the thin metallic wires 108A from being brought into contact with the outside, and therefore the handling work is difficult.
Morever, it was impossible to inspect the semiconductor element as a single unit and all functions thereof after the semiconductor elements were mounted on both surfaces of the circuit board 101. Thus, it is difficult to find out the cause of the failure occurring in the circuit module. Therefore, the highly reliable circuit module cannot be provided.
Furthermore, if a joint of the first semiconductor element 105 fails to work, a second semiconductor element 106 without any problems has been wasted because the second semiconductor element 106 is mounted together with the first one. Accordingly, if the second semiconductor element 106 is, for example, an expensive sensor, this results in an increase in a manufacturing cost.
Moreover, in recent years, thin type packages, called an SIP and a CSP have become available in the market. In particular, the SIP is of a type called a stacked type which is formed by stacking a plurality of chips in a vertical direction, and, in other words, the SIP is of a two-dimensionally arranged type so as to allow a high-performance circuit to be incorporated into one package. However, there are problems of the thickness of a sealing resin, and the warpage of the substrate resulted from the high performance. For example, in a high temperature or humid atmosphere, there is a problem of diminishing the reliability.